HAVANA — On an island where most people have no Internet access, the arrival of mobile phone e-mail service was embraced with joy.

Tens of thousands of Cubans began e-mailing like crazy in March — for days, until the service started to fail, taking much of Cuba’s already shaky voice and text-messaging mobile service down with it.

The island’s aging cellphone towers became swamped by the new flood of e-mail traffic, creating havoc for anyone trying to use the system. Even voice calls by non-subscribers began to drop during conversations. Ordinary text messages arrived days late, or not at all.

Since then, the state telecom monopoly Etecsa has issued a rare apology and the troubles have eased. But problems with the service, dubbed Nauta, offer a rare window into the Internet in Cuba, where the digital age has been achingly slow to spread since arriving in 1996, leaving the country virtually isolated from the world of streaming video, photo-sharing and 4G cellphones.

Cuba’s government blames the technological problems on a U.S. embargo that prevents most American businesses from selling products to the Caribbean country. Critics of the government say it deliberately strangles the Internet to halt the spread of dissent. Other observers offer a less political explanation: a government desperate for foreign exchange is investing little in infrastructure improvements while extracting as much revenue as possible from communications services largely paid for by Cubans’ wealthier overseas relatives.

Experts say that last explanation appears to be the primary culprit in the case of Nauta.

“Cuba is extremely broke,” said Larry Press, a professor of information systems and expert on Cuban telecommunications at California State University, Dominguez Hills. “If they had access to tons of capital, they would probably expand (Internet service) further.”

About 100,000 people — around 5 percent of Cuban cellphone users — had subscribed to the service even though it cost 50 times that of many U.S. data plans.

Radio scriptwriter Lisandra Ayala, 36, stood in line for hours in March outside an Etecsa office, dreaming of zipping e-mails back and forth with her favorite cousin in Canada. Like many Cubans, she has long had a smartphone — a status symbol frequently brought in by visiting relatives.

She paid $1.50 to sign up for a Nauta contract that was supposed to let her send e-mails with the ability to attach photos, but not send video or check the Web. Even the price of $1 per megabyte, many times higher than in virtually any developed country, didn’t deter her.

“I was so excited at first, but then the experience turned into a total disaster,” Ayala said. After a week of decent service, she found it impossible to open the icon for Nauta without trying at least six times; voice calls dropped or didn’t go through, and text messages disappeared mid-air.

“We have been preparing for more than a year,” Hilda Arias, director of Etecsa, told official media late last month. “Customers’ expectations really exceeded our vision.”

She promised that the situation would improve, albeit slowly.

With cellular rates as high as 35 cents a minute for domestic calls, Etecsa earned roughly $500 million last year, revenue that’s been rising slowly since 2008, according to Emilio Morales, a systems engineer who heads the Miami-based Havana Consulting Group, a private consultant that analyzes Cuba’s scanty public information about government revenues and operations
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The group’s studies show that 54 percent of payments to Etecsa come directly from the Cuban diaspora. Morales believes Cubans pay much of the rest out of the estimated $2.6 billion a year in remittances from abroad. And, while most state workers make only $20 a month, a new class of roughly 400,000 independent businessmen and their employees also make heavy use of cellphones for advertising with text-message as well as ordinary business calls.

Authorities here say they are trying to offer a range of new Internet services by year’s end, including mobile Web access and unrestricted home Internet access.

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